On September 14 each year, Christians around the world celebrate the Feast of the Exaltation of the Holy Cross. This feast day originated from the miraculous discovery of the true cross of Christ on September 14,326 by St. Helen, the mother of Emperor Constantine, while she was on a pilgrimage to Jerusalem.
Actually, St. Helen discovered three crosses buried on Golgotha, where Jesus Christ was buried. The true cross was identified because it was found between the two others (those of the two thieves), because it bore the inscription (Jesus of Nazareth, King of the Jews), and because it was the source of numerous miracles.
Beginning with September 14, 347, there was an annual ceremony in the Basilica of the Holy Resurrection, which Constantine had ordered built in Jerusalem. At this annual observance, a relic considered to be the wood of the true cross would be venerated. The bishop "exalted" the cross; that is, he raised it solemnly before the people.
It is from this tradition of exalting the cross that this feast received its name -- the Feast of the Exaltation of the Holy Cross, or literally, its elevation.
The Exaltation of the Cross, then, is a solemn commemoration of the cross and its meaning, as well as an affirmation of the victory of the cross.
Christians today continue to recognize the cross as the source of peace with God and the life and joy which flow from this reconciliation.